Air-brake valve.



No. 630,377. Patented Aug. s, |899. w. B. MANN.

AIR BRAKE VALVE.

(Application led Oct. 5, 1898.).

W /////%/lllllm UNITED STATES PATENT OFFICE.

WILLIAM B. MANN, OF BALTIMORE, MARYLAND.

Ale-BRAKE VALVE.

SPECFIGATON forming part of Letters Patent No. 630,377, dated'August 8, 1899. Application filed October 5, 1898. Serial No. 692,690. (No model.)

T0 all whom, t may concern: r

Be it known that I, WILLIAM B. MANN, a resident of Baltimore, Maryland, have invented anew and useful Improvement in Air- Brake Valves, which improvement is fullyset forth in the following specification.

My invention relates to the triple-valve mechanism for controlling the application of air-brakes on railway-cars, and more particularly to that class of triple valves designed to produce quick serial action ofthe brakes by serially venting the train-pipe into the brake-cylinder. Heretofore in some forms of this class of valves when the actuating-piston of the triple valve has been given its full traverse for the purpose of producing `an emergency application of the brakes a part on the piston has been caused to indirectly open a valve controlling a by-passage lead ing from the train-pipe around the triple valve and into the brake-cylinder, whereby train-pipe air was admitted to the brakecylinder without passing through the triplevalve chamber; but said by-pass valve thus opened by the full traverse of the piston remained open till the return movement of the piston, when it (the by-pass Valve) was closed by a spring. It is desirable that the by-pass valve should close as soon as the train-pipe pressure has been sufficiently reduced to cause the prompt serial action of the next triple valve in the series, Aand it is therefore desirable that the closing movementof the by-pass valve should be automatic and independent of the movements of the triple-valve piston. It is also desirable to avoid the use of springs in the manipulation of the valve mechanism, to the end that the said mechan' ism may depend in all its movements upon the pressure in the train-pipe.

The objects of the present invention are to simplify the construction of triple-valve structures venting the .train-pipe into the brake-cylinder, to provide a by-pass valve that will close automatically without regard to the return throw of the triple-valve piston, and, furthermore, to provide a by-pass valve which will remain seated or will be unseated, as may be desired, when the triple-valve piston is given its full traverse.

With these objects in view my invention consists in a triple valve of any desired construction having a valve-actuating piston, a by-passage leading from the train-pi pe to the brake-cylinder, a valve interposed in said passage, and means `unseating said valve when the triple-valve piston is given its emergency throw, and means automatically seating said Valve regardless of the position of the triple-valve piston.

Further, the invention consists of a triple valve and its actuating-piston, with a bypassage connecting the train-pipe and the brake-cylinder and a valve in said passage having operative relations with the triplevalve piston, whereby the by-pass valve may be unseated or remain seated upon the full `traverse of the triple-valve piston at -the will `is a similar v iew with the parts in position for service or graduatin g application.

. Like letters refer to like parts in all the views, in whichl Y A indicates the valve-casing; B, the triple valve; C, the triple-valve piston; D, the passage leading from the train-pipe; E, the pas sage to the auxiliary reservoir, and F the passage to the brake-cylinder.

G is the exhaust-port leading to the atmosphere, and H is the by-passage leading from the train-pipe to the brake-cylinder and preferablyy formed in the triple-valve casing A, as shown. One side of the triple-valve piston is exposed to pressure from the auxiliary reservoir and the other side to` train-pipe pressure in a common and well-known manner. Formed on the rear or train-pipe side of the triple-valve piston is a plunger B', which projects through an opening in the roo rearend of the piston-cylinder. This opening is' greater in diameter than the plunger B and has formed around its marginavalveseat IQ In arearward extension of the valvecasing Ais formed a cylinder J, Within which plays a piston K, having a hollow stemV 7c, closed at its rear end, but open at its front end-that is, at the end adjacent to the plunger B', which plunger enters the hollow' stem with a loose fit. Surrounding and rigidly attached to the forward end of the hollow stem lo is an annular valve 7c', which normally seats on the valve-seat I, thus closing the passage H from the train-pipe D to the brakeecylinder passage F. The cylinder J is at all times in free communication with the train-pipe through a passage j, formed in the valve-casing, and the interior of the hollow pistonstem in is alsoA .in communication withY the trainpipe by reason of the loose t of the plunger B in said stem, the valve k being normally held seated by reason of the diiferential pressures on the opposite sides thereof, it being of course understood that the passage H is normally in communication with the atmosphere through the exhaust-'port G. Between the valve-seat I and the brake-cylinder passage F andV preferably in the passage H is a spring-pressed check-valve h, opening from the direction of train-pipe pressure toward the brake-cylinder.

The operation of the device is as follows: When it is desired to produce an emergency application of the brakes, the pressurein the train-pipe is quickly lowered at the engineers valve, thus' causing the piston C to suddenly make its'full traverse from the position shown in Fig. l to that of Fig. 2, thereby forcing the plunger B into the hollow stem 7i; and compressing the air contained therein to such an extent as to overcome 'the pressure on the rea-r side of piston K and unseat the valve k'. The valve 7c' being unseated, air from the train-pipe D enters the passage H, raising the check-valve against its light spring, a-nd passes to the brake-cylinder passage F, and at the same time auxiliary-reservoir air enters the brake-cylinder through the passage 'E and the port e. I prefer to construct the port c of much smaller area than the cross-section o'f the'rpassage H in order that the rush of air from the train-pipe through said passage H may not be unduly checked by back pressuredue to the auxiliary-reservoir pressure. By this means I insure the quick lowering of press-ure in the train-pipe, upon which quick serial action depends.v As stated above, the opening or unseating of the valve 7c is due to the fact that the plunger B compresses the air in the hollow stem lo to such an extent as to overcome the train-pipe pressure on the rear of pist-on K. Owing, however, to the loose fit of the plunger vB in the hollow stem lo the air rapidly escapes from the hollow stem, whereupon the compressed air in thc cylinder J acts upon the piston K and seats the valve 7c', thus closingV communication between the train-pipe and the brake-cylinder.

yIn operating the valve for ordinary service application of the brakes and for graduating, the pressure inthe-train-pipe is lowered but slightly and.' the'triple-valve piston moves slower than in emergency applications and only'makes a partial traverse, the parts taking the positions shown in Fig. 3. In this case Y"t'heplunger B' enters the hollow stem k so gslowly and for such a short distance that the air in the stem is never compressed to a degreesuicient toY unseat the valve la', but es- 'capes from the stem past therplunger, thus maintaining equilibrium of pressure in the train-pipe and the hollow stem lo. If the pressure in the-train-pipe is slowly reduced", the triple-valve piston may make its-full traverse Without unseating the valve lo', and the full power of auxiliarypreser'voir pressure may thus be secured without opening thepassage from the train-pipe to the brake-cylinder. This is particularly advantageous when for any reason it isdesiredto apply full auxiliary pressure to the brakes, but without the suddeness of action occurring 'in an emergency stop.- Should the train break in two or a damaging leak occur in the trainpipe, the check-valve h would prevent the escape of air from the'brake-cylinder and consequent release of the brakes.

Having thus described my invention, I claim as new and desire to secure by Letters Patentu l. The combination of a triple-valve casing having ports leading tothe train-pipe, the auxiliary reservoir and the brake-cylinder, a triple valve and its operating-piston working in said casing, with a by-passage connecting thel train-pipe with the brake-cylinder, a differential piston-valve controlling said passage, and means operating on thefemergeney ltraverse of lthe triple-valve piston to augment the air-pressure on the train-pipe side of said dierential piston-valve to a point beyond train-pipe pressure, substantially as described.

2. The combination of aftrafin-pipe, an-auxiliary reservoir, a brake -cylinder, a triple valve and its operating-piston, with a difEerential piston-valve controlling a passage leading around the-triple-valve chamber from the train-pipe to the brake-cylinder, and 'means alternating the preponderance of air-pressure per unit of surface on the piston-valve when and only when the triple-valve piston makes `its full traverse for emergency stops, substantiallyas described.

3. The combination of the train-pipe, auxiliary reservoi r, brake-cylinder, triple valve and its operating-piston, with a passage leading from the train-pipe around the triple- `valve casing to the brake-cylinder, adierl,ential piston-valve oontrolling`said passage IOC IIO

and held to its seal; by train-pipe pressure, and means acting on the emergency throw of Johe triple-Valve piston to first augment and then lower the pressure on the opening side of said diierentia piston-Valve when the pressure in the train-pipe is suddenly lowered, substantially as described.

In testimony whereof I have signed this speciioation in the presence of two subscribing Witnesses.

WILLIAM B. MANN.

VVtnesses:

THos. KENT BRADFORD, REEVE LEWIS. 

